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Makwizard
Trad climber
durham
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Topic Author's Original Post - Oct 16, 2008 - 05:41pm PT
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I am currently conducting research at Duke University to analyze and redesign cam lobes. The end goal is to improve a cam's ability to hold in soft rock and flaring cracks. I have just begun my research but will be continually posting updates of my findings on my [url="http://www.duke.edu/~mak25/research.html"]cam research page[/url].
Thanks.
[url="http://www.duke.edu/~mak25"]my homepage[/url].
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Russ S.
climber
Seattle, WA
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Oct 16, 2008 - 07:25pm PT
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Dude, look at the pictures on his site, appears he does climb... what's the problem???
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Moof
Big Wall climber
A cube at my soul sucking job in Oregon
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Oct 16, 2008 - 07:34pm PT
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Your research page looks very extensive so far.
Mind sharing, even vaguely, what you hope to add to the 30+ year old design of the 4 cam logarithmic spiral SLCD?
Offset friends never became popular. Offset aliens fill the pin scar void nicely. You can get different alloys from steel to soft aluminum (whatever aliens are made of...), 6061 for most, 7075 for a few, so material choice is already out there.
Cam angle varies from 12-15 degree as well.
Sounds to me like you want to invent a rounder wheel.
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Dr. Rock
Ice climber
http://tinyurl.com/4oa5br
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Oct 16, 2008 - 08:43pm PT
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Man, tough room, ehh?
I am interested in this also.
The initial force on the cam acts to jerk it out of the rock.
It is an impulse.
If the cams do not have time to engage, the impulse will pull it out of the crack.
Friction is needed to make the cam wheels stick.
This requires a force from the rope via the cam.
Ways to improve the friction coef was on my small mind.
Sharper teeth, angled such that they are not sitting perp to the rock like the stock cams.
Steel wheels so the teeth don't get worn.
In order to save weight, maybe just a steel cover over the Al wheel would work.
That way you could change them when they wear.
You could even have different teeth patterns for different rock.
Coarser teeth for choss and sandstone, fine teeth for smooth Yosemite granite.
Ray designed that thing about 10 million years ago.
If they put as much money into climbing gear as the space program, you would not recognize the new equipment, thats how far behind the times we are.
So just say Yes to new gear and research.
And don't let the bastards get you down.
But then again, climbing is pretty simple, you have gravity, you have the rock, and you have you.
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noshoesnoshirt
climber
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Oct 17, 2008 - 02:25am PT
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Steel's gonna decrease your Cf, aluminum is more malleable thus "sticking" a bit better.
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Dr. Rock
Ice climber
http://tinyurl.com/4oa5br
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Oct 17, 2008 - 04:23am PT
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Yes, that makes sense.
What about tooth sharpness?
I think a hardened steel gear plate could be sharpened to the point where it would grab a lot better than the rounded teeth you see on worn cams?
I am thinkin razor sharp hardened steel teeth, cut at two angles, one angle down, and one angle to make the teeth diagonal to the
wheel.
This would present more of the tooth surface to the rock, by a factor of 1.4 if you use 45 degrees.
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Chris2
Trad climber
The Gunks to Joshua Tree
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Oct 17, 2008 - 08:31am PT
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Sounds like a fun/interesting research project. Don’t let the fact that some will say you are “recreating the wheel,” get you down.
Most climbers will be interested more in a cam that is useful in flaring cracks than soft rock. When you refer to “soft rock” I assume you mean sandstone. Most cams get stuck too easily, as it is, in soft rock.
Good luck.
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Prod
Big Wall climber
A place w/o Avitars apparently
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Oct 17, 2008 - 09:02am PT
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Interesting. Also need to take into mind the effect of the cam on the soft rock.
Prod.
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Chris2
Trad climber
The Gunks to Joshua Tree
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Oct 17, 2008 - 09:11am PT
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For sure. Someone on here most have photo's of cams "tracking" in sandstone cracks?
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adatesman
Trad climber
philadelphia, pa
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Oct 17, 2008 - 09:46am PT
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A couple quick thoughts in no particular order...
1. The post above re: steel having a lower coefficient of friction is correct and why steel lobes won't work so well (unless you drop the cam angle way down to something like 4 or 5 degrees)
2. I have yet to see a compelling argument re: the need for teeth. While they do make it easier for the lobes to catch on crystals, I'm not convinced that action provides a significant increase in the ultimate holding power. I'm open to discussion though....
3. Sharp teeth will decrease the area the load is applied over, which increases the risk of smashing or breaking off the tooth or scarring the rock if the tooth doesn't deform or break off.
4. There is an interesting patent that no one has picked up yet (to my knowledge) that nicely deals with increasing the friction of cam lobes by mounting a high friction insert on the bearing surface of the cam lobe. Its US Patent 20060231708 and makes for interesting reading. Clicky!
5. Spend some time reading and studying the pictures at the Nuts Museum. Lots of interesting designs described/pictured there for inspiration. Clicky!
6. Spend some time on the US Patent Office's website searching through existing patents on gear. Lots of inspiration to be had there as well. Clicky!
7. There's plenty of ways to improve on current cam designs, so don't get discouraged by people that say you're trying to reinvent the wheel. Personally, I've been playing around with it a while now and have found a couple good designs (patented one, working on another). My suggestion for your process would be to take an idea and model it mathematically (Mathematica, Matlab, etc) to make sure that the angles still work out before bothering with solid modeling or making prototypes. Many solid modeling packages won't do logarithmic spirals natively, so you'll end up importing data points for the spiral anyway and might as well do all the math elsewhere. Plus you can then have the math program do all sorts of funky things (increasing/decreasing angle spirals, compound spirals, etc) and then just dump out a single data file to import and avoid having to piece it all together by hand in the modeling program. Makes life much easier.
Anyway, good luck....
-a.
(edit to fix the links)
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TradIsGood
Chalkless climber
the Gunks end of the country
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Oct 17, 2008 - 11:51am PT
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I will just toss this out there...
Classical friction coefficient analysis deals with normal and tangent force (the ratio being the fiction coefficient).
That is a pretty much one plane against another simple problem.
For protection, "compliance" - the ability for two non-planar materials to fit together can increase the maximum pre-slip tangent force. (A nut in a constriction is not really relying much on friction coefficient - at the extreme end of the compliance versus friction spectrum - though behind a flake it might become important!)
Think skin on sandstone, for example. Skin is pretty soft, but moist skin is more compliant than dry skin - cosmetic industry knows this, even if most climbers do not.
But compliance also introduces shear resistance - as alluded to a bit above. Tearing off teeth or rippling out crystals at least temporarily will limit or reduce the maximum tangent force.
Best of luck. I suspect you may be able to find improvements.
:-)
You ever seen those hydraulic pads used in auto accident rescue work? Before Nike, nobody ever put a pump in sneakers (I think).
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MOsucks
Mountain climber
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Oct 17, 2008 - 12:45pm PT
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Ya know what the climbing industry really needs is a good metallurgist.
Every time I buy gear I look at and say, well they could have made this lighter and stronger by just varying the materials properties.
Look at aliens, ok so why in the world would you use an aluminum and do no heat treatment on it? If they really want less strength than use less material and do a heat treatment, >less weight...
Man I could rant for ever.
So I guess the reason is they can't afford a good metalurgist, hell half of the industries seeking us can't afford us and we just go to the highest bidder. A friend of mine with just a B.S. in Metallurgical Engineering got his first job making 75,000. Materials Science bastards just don't understand physical metallurgy.
In conclusion there man, go talk to the crappy materials science program you have there (if you even have one at Duke) and then you can get some good help.
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adatesman
Trad climber
philadelphia, pa
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Oct 17, 2008 - 01:20pm PT
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Hey MOsucks,
Happen to have a source for the CCH no heat treatment thing? They say on their website that the lobes are 6061-T6, which is heat treated when the material is manufactured (precipitate hardened, if I remember correctly). I wouldn't be all that surprised if something they claim on the website was incorrect though.
Actually, I've got a couple scrap lobes from a red Alien in my parts pile, so if anyone has access to a hardness tester we could figure out what state of hardness they're in rather easily (T6 should be ~60 Rockwell B scale).
I agree with your assessment of needing to get materials engineers involved though... Lots of fun stuff that can be done by simply picking the right material.
-a.
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JuanDeFuca
Big Wall climber
Stoney Point
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Oct 17, 2008 - 01:38pm PT
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Seems to me if it is a Masters in Mech E your project should be a bit more difficult. Maybe you can solve the mystery of Friend chatter and walking that parallel cracks produce.
Juan
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MOsucks
Mountain climber
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Oct 17, 2008 - 01:47pm PT
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Well the aliens I have used deffinatly did not seem like T6. A T6 on this should be about rockwell b of 50.
Correct on the precipitation age-hardening, the T6 is a designation of a temper stage of aluminum though.
If you want to send them to me I can get those hardness measurements and even some micrographs to see what they have in fact done to them.
And thanks for agreeing with me.
I don't see how anybody couldn't agree that some of the biggest developments can be had in the materials
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Moof
Big Wall climber
A cube at my soul sucking job in Oregon
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Oct 17, 2008 - 02:24pm PT
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DMT,
Point is simply that this dude posted the exact same message in three threads. He has not posted here before, and so far has not responded. His "research" page is void of anything but a vague mission statement.
Attacking a 30 year old fortified hill using only a vague mission statement, and not even some basic statement of the percieved problems is very weak sauce.
Since Ray (the chiseler) Jardine came up with his Friends ~30 years ago we have indeed seen neat innovation. Camalots insteaded the expansion range from ~1.5:1 to ~1.7:1, while also increasing the contact area (large radius of contact for a given crack width and cam angle). Max Cams employ a compound lever to elegently get to a 2:1 range. Link cams went Rube Goldberg to get up in the 2.5:1 region.
So if junior wants to spew about his new innovation, great. But if he wants us to do his homework for him, then I'd rather he take his spam elsewhere.
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adatesman
Trad climber
philadelphia, pa
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Oct 17, 2008 - 02:43pm PT
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Not to defend the guy, but he has posted more info on his site since yesterday so take another look. Nothing groundbreaking though, so my guess is that its undergrad work rather than masters.
MOsucks- drop me an email (check my profile for my address) with your snailmail address and I'll get a lobe or two out to you early next week. I'm kinda curious as well.
-a.
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MOsucks
Mountain climber
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Oct 17, 2008 - 06:06pm PT
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I don't see anywhere where he says he is in grad school. It is probably senior design for a bachelors degree. Don't be too hard at least someone in academics is trying to do something, plus he is from Duke (not really known for engineering). Besides who knows maybe he can come up with something, I just hope he doesn't expect us to give him our ideas to claim as his.
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Mighty Hiker
Social climber
Vancouver, B.C.
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Oct 17, 2008 - 06:17pm PT
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adatesman: "I have yet to see a compelling argument re: the need for teeth."
Wolf to Red Riding Hood: "The better to eat you with, my dear."
Though I've also heard that teeth help in wet, dirty, and (especially) icy cracks. Essentially, where the coefficient of friction is reduced.
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Dr. Rock
Ice climber
http://tinyurl.com/4oa5br
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Oct 17, 2008 - 06:39pm PT
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Who cares who started the thread, we are here now.
There is a "no man's land" when it comers to friction.
As you know, static friction is where the cam does not moved, it has been jerked into action.
There is dynamic friction, this is friction between a sliding object against another.
Well. right in between the two, is "no man's land."
This is like gravity, they do not know how it works, only that it is there.
The only way to find out about something that has no formulas attached to it is to experiment.
One good experiment is worth a thousand theories, we all know that.
When a dragster takes off from the line, there is a point where the rubber molecules are doing strange things.
This is in the zone between static and dynamic friction.
The rubber is almost in a liquid state.
Companies have been studying this for years in order to improve racing tires.
This is also the same region where a cam is deciding to either stay in the crack and grip, or get yanked out do to the friction not being high enough.
So if you play with different teeth, and throw some bricks off a cliff, you may be able to find something more bomber.
Hey, thats it!
Rubber, not steel.
I was thinking in the wrong direction.
A thin coat of rubber would provider the friction at the critical point where thee rope pulls on the cam.
Then the wheel could take over.
Maybe replaceable pads like brake shoes?>
Trick would be finding a rubber that would hold up.
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